In a laser diode, in order to drive each emitter independently, an isolation trench to electrically isolate each emitter from an adjacent emitter is provided between emitters adjacent to each other. The width of the isolation trench varies according to the laser type. In the case of a narrow pitch type laser in which the beam pitch is about several tens of μm, the width of the isolation trench is only about several μm. Thus, in such a case, it is extremely difficult to provide a wiring layer that links a stripe electrode on the emitter (ridge section) with the both sides surrounded by the isolation trench, to a pad electrode formed in a location apart from the ridge section in the narrow isolation trench. Therefore, as described in Japanese Unexamined Patent Application Publication No. 2000-269601, in general, an insulating material is embedded in the isolation trench, and the foregoing wiring layer is provided on the insulating material.